Hi

The other thing to watch out for is the temperature coefficient. Some of the 
high K materials move a *lot* with modest changes in temperature. There are 
indeed industry standards on what a given dielectric code should be. In some 
cases there have ben liberties taken interpreting the codes. You really need to 
go back to the original data sheet on each part to see what the temp co 
actually is. 

In a modestly warm box (say 60 C) the net effect between voltage and 
temperature may be that you have < 1/4 your original capacitance.

Bob


On Jan 16, 2011, at 5:15 PM, Poul-Henning Kamp wrote:

> In message <4d336a19.40...@freenet.de>, "Dr. Frank Stellmach" writes:
> 
>> High cap value Ceramics are available since years, [...]
> 
> Can you clarify one thing for me: When I studied datasheets for these
> it looked like they drop 50% of their capacitance at a DC voltage
> of 10-20V.
> 
> Doesn't that make them a so-so bargain for power supply bulk capacitance ?
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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